PSI - Issue 59

Imbirovych Nataliia et al. / Procedia Structural Integrity 59 (2024) 413–419 2 Imbirovych Nataliia, Zvirko Olha, Povstianoi Oleksandr, Tkachuk Valentyna / Structural Integrity Procedia 00 (2023) 000 – 000 1. Introduction Titanium and its alloys are considered promising materials for medical applications due to their mechanical and corrosion properties and biocompatibility as well. In order to improve the functional properties of such alloys, their surface is modified by various methods, in particular, using plasma-electrolytic oxidation (PEO). The main feature of the PEO method is the wide possibility of controlling coatings' physical and mechanical properties by changing the electrolyte composition and the synthesis parameters. It enables obtaining coatings with the desired properties. The PEO method is widely used for aluminium (Raj and Mubarak Ali (2009), Erfanifar et al. (2017), Imbirovych et al. (2021), Kovalchuk et al. (2023)), magnesium (Arrabal et al (2008), Nykyforchyn et al (2008), Guo et al (2009), Mori et al (2014), Oleshko et al. (2020)), zirconium (Pauporté et al (2005), Klapkiv et al (2006), Nykyforchyn et al (2008), Lee et al (2011), Cheng et al (2011)) and titanium (Klapkiv et al (2006), Diamanti et al (2007), Nykyforchyn et al (2008), Yao et al (2008), Galvis et al (2015), Imbirovich et al. (2015), Kyrylenko et al. (2023)) alloys. The authors indicate an enhancement of the physical and mechanical properties of the obtained oxide-ceramic coatings (OCC). It is known that titanium alloys are very promising in implantology due to their biocompatibility with human tissue, as demonstrated by Geetha et al. (2009), Galvis et al. (2015), and others. Titanium alloys are suitable for generating highly biocompatible films on their surface. Other important properties of materials used for fabricating implants are mechanical and fatigue resistance properties, wear resistance, and corrosion resistance in the biological environment (Geetha et al. (2009), John et al. (2016), Yavari et al. (2016), Tkachuk et al. (2022), Kyrylenko et al. (2023), Imbirovych et al. (2023), Pohrelyuk et al. (2023)). Osseointegration is important for implant materials and their coatings. Under operating conditions, the implant surface is affected by loads. As a result, this can lead to increased internal stresses and coating damage or fracture. Therefore, hardness is an important functional property of biocompatible oxide ceramic coatings synthesized on titanium alloys. It is very important to know the correlation between thickness and hardness to use oxide ceramic coatings on Ti alloys. The properties of the coatings obtained using the PEO method are significantly influenced by a change in electrolyte components, synthesis time, and current density. In this work, the effect of the composition of the electrolyte for the PEO of the VT8 titanium alloy and parameters of the synthesis on the surface characteristics, namely hardness and thickness of the formed OCC, has been investigated. The possibility of an evaluation of hardness by a non-destructive method is also analysed. 2. Methods of experimental research The OCС formation by the PEO method and the coating’s properties were investigated on titanium alloy VT 8 samples with a total surface area of 1 cm 2 used for the experiment. The synthesis of OСС was performed using the IMPELOM-1 installation (Fig. 1, a); it includes a current control unit and a power source (1), a bath for electrolyte (2), and cooling units (3). A stainless steel bath is a cathode; it is filled with an electrolyte. Using measuring devices (voltmeter and ammeter), the values of the time dependence of the voltage of the anode and cathode currents were recorded. Distilled water was used for preparing electrolytes. They were constantly mixed during experiments by using air.

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